One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(5,8)(9,10)(11,20)(12,16)(13,22)(14,18)(15,19)(17,23)(21,24)(25,26)(27,34)(28,29)(30,31)(32,37)(33,38)(35,36)(39,40) involution — undirected(1,2,4,6)(3,5,7,8)(11,12)(13,23)(16,20)(17,22)(26,31)(28,38)(32,34)(35,40)(1,3)(2,5)(4,7)(6,8)(9,11,15,12)(10,16,19,20)(13,21,23,18)(14,17,24,22)(25,27,30,37)(26,32,31,34)(28,35,38,40)(29,39,33,36)(1,2)(3,5)(4,6)(7,8)(9,12,15,11)(10,16,19,20)(13,18,23,21)(14,17,24,22)(25,28)(26,33)(27,35)(29,31)(30,38)(32,36)(34,39)(37,40)(1,3)(2,5)(4,7)(6,8)(9,13,15,23)(10,17,19,22)(11,21,12,18)(14,16,24,20)(25,28)(26,33)(27,35)(29,31)(30,38)(32,36)(34,39)(37,40)(9,14,15,24)(10,18,19,21)(11,22,12,17)(13,16,23,20)(25,29,30,33)(26,28,31,38)(27,36,37,39)(32,40,34,35)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.